Use nmake's inline file creation to automate .rsp files.

Use nmake's inline file creation to automate .rsp files.

This is noticeably faster than a sequence of 'echo' commands, because
the file gets created all in one go. The most natural approach to this
job would also hide the file's contents, but doing it this way with a
'type' command lets me see the file on nmake's standard output, so
that the build log should still contain everything useful for
debugging build problems.